Volume 1 - Chapter 24: OSPF Neighbors and Route Selection

Question 1

True or False:

Routers can become OSPF neighbors if they reside in different areas, but are connected to the same LAN segment.

Answer 1

False

Neighbors must be in the same area.

Question 2

Which OSPF setting mismatches will allow neighbors to form, but prevent them from exchanging routes?

Answer 2

Mismatched MTU settings
Mismatched OSPF network type (broadcast and P2P)
Both neighbors using priority 0

Question 3

What are the commands to set the IPv4 and IPv4 MTUs for an interface?

Answer 3

ip mtu

ipv6 mtu

Question 4

How does a router make a forwarding decision when a router has 2 equal-cost OSPF routes to the same subnet?

Answer 4

The router will choose the next hop based on the destination IP address. For example,

Destination 192.168.10.3 /24 might be sent via Gi0/0/1
Destination 192.168.10.4 /24 might be sent via Gi0/0/2

Question 5

How does a router make a forwarding decision when a router has 2 routes learned to the same destination, but each is learned via different routing protocols?

Answer 5

By choosing the routing protocol with a lower administrative distance.

Question 6

What is the administrative distance of a route learned by RIP?

Answer 6

120

Question 7

What is the administrative distance of a route learned by External BGP (eBGP)?

Answer 7

20

Question 8

What is the administrative distance of a route learned by DHCP?

Answer 8

254

Question 9

What is the administrative distance of a route learned by IS-IS?

Answer 9

115

Question 10

What is the administrative distance of a route that is statically configured?

Answer 10

1

Question 11

What is the administrative distance of an internal route learned by EIGRP?

Answer 11

90

Question 12

What is the administrative distance of a route learned by Internal BGP (iBGP)?

Answer 12

200

Question 13

What is the administrative distance of a route learned by OSPF?

Answer 13

110

Question 14

What is the administrative distance of a directly connected route?

Answer 14

0

Question 15

What is the administrative distance of an external route learned by EIGRP?

Answer 15

170

Question 16

What administrative distance value is unusable?

Answer 16

255

Question 17

Describe the process of route redistribution.

Answer 17

A small set of routers that take routes learned from one routing protocol and advertises them via a different routing protocol.

Question 18

How does a router make a forwarding decision when it contains 2 routes with the same administrative distance and cost, but the destination subnets overlap with each other?

Answer 18

The router will choose the route with the lowest (more specific) prefix length.

Question 19

A technician checks the routing table to the destination IP of 10.72.4.5 and gets two results:

10.72.4.0 /24 via 192.168.10.5
10.72.0.0 /16 via 192.168.10.6

Which route will be chosen?

Answer 19

The route via 192.168.10.5 because it has the longer (more specific) prefix length.

Question 20

A technician performs the command “show ip route” and sees the following:

192.168.50.16 /28 [110/96] via 172.67.3.2, 18:06:02, Te0/0/1

What is indicated by the section [110/96]?

Answer 20

The administrative distance is the first value of 110, the second value represents the metric of 96